Pyridomorphinans, thienomorphinans and use thereof

ABSTRACT

Compounds represented by the formulae:  
                 
 
wherein each of Y, X and R individually is selected from the group consisting of hydrogen, hydroxy, halo, CF 3 , NO 2 , CN, NH 2 , COR 1  and CO 2 R 2  wherein R 1  is selected from the group consisting of alkyl, aryl, alkaryl, and NH 2 , and R 2  is selected from the group consisting of alkyl, aryl and aralkyl, and provided that at least one of Y, X and R is other than H; and pharmaceutically acceptable salts thereof are provided. Compounds of the above formula are useful as analgesics for treating pain, as immunomodulators and for treating drug abuse.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made under Grant DA 08883 from the National Instituteon Drug Abuse.

TECHNICAL FIELD

The present invention relates to certain pyridomorphinan andthienomorphinan compounds and more particularly to naltrexone-derivedpyridomorphinan and thienomorphinan compounds. Compounds of the presentinvention exhibit high antagonist activity at the δ receptor. Moreover,various compounds of the present invention possess μ agonistcharacteristics. Compounds of the present invention areespecially-useful as analgesics for treating patients suffering frompain, useful as drugs to modulate the development of tolerance anddependence to μ agonists, modulate the behavioral effects of drugs ofabuse, and to elicit immunomodulatory effects.

BACKGROUND OF INVENTION

Opioid receptors belong to the superfamily of G-protein coupledreceptors that mediate the analgesic and other pharmacological actionsof morphine and related opioid drugs. In the past, it was believed thatonly a single opioid binding site existed. The existence of at leastthree distinct subtypes of opioid receptors, designated μ, δ and κreceptors, in the central nervous system and periphery is now wellestablished. Human μ, δ and κ receptors have been cloned and have beenshown to belong to the G protein-coupled receptor (GPCR) superfamily.

The existence of three distinct opioid receptor types, μ, δ and κ, isconfirmed by the recent cloning of these three opioid receptors frommouse, rat and human cDNAs. All three of the opioid receptor types arelocated in human brain or spinal cord tissues and each has a role in themediation of pain. Opiates are used extensively for the treatment ofpain and are the most effective analgesic agents available. Morphine andits analogues currently prescribed as potent analgesics are μ selectiveligands. The general administration of these medications is limited byside-effects such as respiratory depression, depression ofgastrointestinal motility and development of tolerance and physicaldependence.

The development of potent and selective antagonist and agonist ligandsfor each of these opioid receptor subtypes has been the goal ofmedicinal chemists for many years because of their potential usefulnessas pharmacological tools and as therapeutic agents. Among the μ, δ and κreceptors, the development of antagonist and agonist ligands actingthrough the δ receptor has become the focus of research in recent yearsdue to the therapeutic potential of opioid δ ligands. Various studiessuggest that δ selective agonists could be potentially useful asanalgesics devoid of side effects such as respiratory depression andphysical dependence side effects. Selective antagonists of δ receptorshave been shown to display immunomodulatory effects as well asmodulatory effects on the actions of drugs of abuse such as cocaine andmethamphetamines. Moreover, recent studies using rodents havedemonstrated that δ opioid antagonists are capable of preventing thedevelopment of tolerance and dependence to μ agonist such as morphinewithout interfering with the μ opioid antinociception.

It has been found that a number of ligands synthetically derived fromnaltrexone display significant selectivity toward the δ receptors. Amongthese, the indolomorphinan naltrindole is presently widely used as δselective antagonist ligand, and other ligands such as its5′-isothiocyanate derivative, benzofuran analog, and(E)-7-benzylidenenaltrexone have been useful in the pharmacologicalcharacterization of δ opioid receptor subtypes.

Continuing efforts exist for developing subtype selective nonpeptideopioid ligands.

SUMMARY OF INVENTION

The present invention relates to compounds represented by the followingformulae:

wherein each of Y, X and R is individually selected from the groupconsisting of hydrogen, hydroxy, alkyl, alkoxy, aryl, halo, CF₃, NO₂,CN, NH₂, COR¹ and CO₂R², wherein R¹ is selected from the groupconsisting of alkyl, aryl, aralkyl and NH₂; and R² is selected from thegroup consisting of alkyl, aryl and aralkyl; and provided that at leastone of Y, X and R in formula I is other than hydrogen; andpharmaceutically acceptable salts thereof.

The present invention also relates to treating a patient suffering frompain which comprises administering to the patient a pain treatingeffective amount of at least one of the above compounds.

A further aspect of the present invention relates to treating a patientin need of an immunomodulatory agent which comprises administering tothe patient an immunomodulatory effective amount of at least one of theabove compounds.

A still further aspect of the present invention relates to treating apatient suffering from drug abuse which comprises administering aneffective amount for treating drug abuse of at least one of the abovecompounds.

Another aspect of the present invention is concerned with treating apatient suffering from dependence on or tolerance to a μ agonist whichcomprises administering to the patient at least one of the abovecompounds in an amount effective to modulate the tolerance to ordependence on μ agonists, such as morphine.

Still other objects and advantages of the present invention will becomereadily apparent by those skilled in the art from the following detaileddescription, wherein it is shown and described preferred embodiments ofthe invention, simply by way of illustration of the best modecontemplated of carrying out the invention. As will be realized theinvention is capable of other and different embodiments, and its severaldetails are capable of modifications in various obvious respects,without departing from the invention. Accordingly, the description is tobe regarded as illustrative in nature and not as restrictive.

BEST AND VARIOUS MODES FOR CARRYING OUT INVENTION

The compounds according to the present invention are represented by thefollowing formulae:

wherein each of Y, X and R is individually selected from the groupconsisting of hydrogen, hydroxy, halo, CF₃, NO₂, CN, NH₂, COR¹ and CO₂R²wherein R¹ is selected from the group consisting of alkyl, aryl, aralkyland NH₂; and R² is selected from the group consisting of alkyl, aryl andaralkyl; and provided that at least one of Y, X and R in formula I isother than hydrogen; and pharmaceutically acceptable salts thereof.

The alkyl groups typically contain 1 to about 6 carbon atoms, and moretypically 1 to about 3 carbon atoms, and can be straight, branched-chainor cyclic saturated aliphatic hydrocarbon groups.

Examples of suitable alkyl groups include methyl, ethyl and propyl.Examples of branched alkyl groups include isopropyl and t-butyl.Examples of suitable cyclic aliphatic groups typically contain 3-6carbon atoms and include cyclopentyl and cyclohexyl. Examples of arylgroups are phenyl and naphthyl. Examples of aralkyl groups includephenyl C₁₋₃ alkyl such as benzyl.

Pharmaceutically acceptable salts of the compounds of the presentinvention include those derived from pharmaceutically acceptable,inorganic and organic acids and bases. Examples of suitable acidsinclude hydrochloric, hydrobromic, sulfuric, nitric, perchloric,fumaric, maleic, phosphoric, glycollic, lactic, salicyclic, succinic,toluene-p-sulfonic, tartaric, acetic, citric, methanesulfonic, formic,benzoic, malonic, naphthalene-2-sulfonic, trifluoroacetic andbenzenesulfonic acids. Salts derived from appropriate basesinclude-alkali such as sodium and ammonium.

The preferred compounds of the present invention represented by formulaI contain a R constituent other than hydrogen the preferred compounds ofthe present invention represented by formula II contain NH₂ as the Xsubstituent.

Some specific compounds according to the present invention are thefollowing:

-   5′-Bromo-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxypyrido[2′,3′:6,7]morphinan    (referred to herein also as 7b).-   5′-Cyano-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxypyrido[2′,3′:6,7]morphinan    (referred to herein also as 7c).-   5′-Carbethoxy-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxypyrido[2′,3′:6,7]morphinan    (referred to herein also as 7d)-   17-(Cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxy-5′-nitropyrido[2′,3′:6,7]morphinan    (referred to herein also as 7e)-   5′-Amino-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxypyrido[2′,3′:6,7]morphinan    (referred to herein also as 7f)-   5′-Amino-4′-cyano-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxythieno[2′,3′:7,6]morphinan    (referred to herein also as 8a).-   5′-Amino-4′-carbomethoxy-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxythieno[2′,3′:7,6]morphinan    (referred to herein also as 8b).-   5′-Amino-4′-carbethoxy-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxythieno[2′,3′:7,6]morphinan    (referred to herein also as 8c).-   5′-Amino-4′-benzyloxycarbonyl-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxythieno[2′,3′:7,6]morphinan    (referred to herein also as 8d).-   5′-Amino-4′-aminocarbonyl-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxythieno[2′,3′:7,6]morphinan    (referred to herein also as 8e).-   5′-Amino-4′-benzoyl-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxythieno[2′,3′:7,6]morphinan    (referred to herein also as 8f)

Compounds of the present invention represented by formula I can besynthesized from naltrexone by condensation with, for instance, asubstituted acrolein as illustrated in Scheme 1 below.

By way of example, 5′-bromo-, 5′-cyano-, and5′-carbethoxypyridomorphinans (referred to herein below as 7b-d) weresynthesized by using the corresponding 2-bromo-, 2-cyano-, or2-carbethoxy-3-(dimethylamino)acroleins in the condensation reactionwith naltrexone (Scheme 1).

Methods for producing the acrolein intermediates used for synthesis ofpyridomorphinans of the present invention are known. For example, Gaiset al, Acetylenes with Electron-Donor and Electron-Acceptor Groups,Helv. Chim. Acta. 1969, 52, 2641-2657, describes a procedure for making2-bromo-3-(dimethylamino)acrolein. Reichardt et al,Vilsmeier-Formylation of Acetonitrile 1970, 538 discloses a procedurefor making 2-cyano-3-(dimethylamino)acrolein. Kim et al, A New Synthesisof 5,7-Dicarboxy-2,1-benzisoxazolin-3-one, J. Heterocyclic Chem. 1985,22, 127-128 describes methodology for making2-carbethoxy-3(dimethylamino)acrolein.

In addition, compounds referred to hereinbelow as 7e and 7f weresynthesized by modifying the method described by Tohda et al,Nucleophilic Reaction upon Electron-Deficient Pyridone Derivatives X.One-Pot Synthesis of 3-Nitropyridines by Ring Transformation of1-Methyl-3,5-dinitro-2-pyridone with Ketones or Aldehydes in thePresence of Ammonia, Bull. Chem. Soc. Jpn. 1990, 63, 2820-2827, forproducing nitropyridine by using 3,5 dinitro-1-methyl-2-pyridone whichproduced the nitro compound 7e which was reduced to the amine 7f.

Compounds of the present invention represented by formula II can besynthesized from naltrexone by condensation with active methylenenitrites and elemental sulfur in the presence of a base as illustratedby Scheme 2 below. This is a modification of a reaction scheme forsynthesizing thiophenes described by Gewald et al, 2-Aminothiophenesfrom Active Methylene Nitriles, Carbonyl Compounds and Sulfur, Chem.Ber. 1966, 99, 94-100.

The following non-limiting examples are presented to further illustratethe present invention.

EXAMPLE 1 Preparation of5′-Bromo-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxypyrido[2′,3′:6,7]morphinan(7b)

A mixture of naltrexone (1.0 g, 2.9 mmol),2-bromo-3-(dimethylamino)acrolein (1.04 g, 5.9 mmol) and ammoniumacetate (0.92 g, 12.0 mmol) in glacial acetic acid (15 mL) was heatedunder reflux under an atmosphere of argon for 3 days. The acetic acidwas removed under reduced pressure and the residue was treated withwater and the mixture was made basic with concentrated aqueous NH₄OH.The mixture was extracted with CH₂Cl₂ (3×80 mL). The combined organicextracts were washed with brine, dried (Na₂SO₄) and the solvent wasremoved under reduced pressure. The residue was purified by flashchromatography over a column of silica using CHCl₃—MeOH (99.5:0.5)followed by CHCl₃—MeOH—NH₄OH (99:0.5:0.5) as the eluent to obtain 7b(0.212 g): mp 266-268° C. dec; TLC, R_(f)0.43 (CHCl₃—MeOH—NH₄OH,95:5:0.5).

EXAMPLE 2 Preparation of5′-Cyano-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxypyrido[2′,3′:6,7]morphinan(7c)

A mixture of naltrexone (1.0 g, 2.9 mmol),2-cyano-3-(dimethylamino)acrolein (0.73 g, 5.9 mmol) and ammoniumacetate (0.92 g, 12.0 mmol) in glacial acetic acid (15 mL) was heatedunder reflux under an atmosphere of argon for 3 days. The acetic acidwas removed under reduced pressure and the residue was treated withwater and the pH of the mixture was adjusted to 8 with concentratedaqueous NH₄OH. The mixture was extracted with CH₂Cl₂ (3×80 mL). Thecombined organic extracts were washed with brine, dried (Na₂SO₄) and thesolvent was removed under reduced pressure.

The residue was purified by flash chromatography over a column of silicausing CHCl₃—MeOH—NH₄OH (98.5:1.0:0.5) as the eluent to obtain 7c (0.142g): mp 152-158° C. dec; TLC, R_(f) 0.21 (CHCl₃—MeOH—NH₄OH, 95:5:0.5).

EXAMPLE 3 Preparation of5′-Carbethoxy-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxypyrido[2′1,3′:6,7]morphinan (7d)

A mixture of naltrexone (1.0 g, 2.9 mmol),2-carbethoxy-3-(dimethylamino)acrolein (1.0 g, 5.9 mmol) and ammoniumacetate (0.92 g, 12.0 mmol) in glacial acetic acid (15 mL) was heatedunder reflux under an atmosphere of argon for 30 h. The acetic acid wasremoved under reduced pressure and the residue was treated with waterand the pH of the mixture was adjusted to 8 to 9 with saturated aqueousNaHCO₃. The mixture was extracted with CH₂Cl₂ (4×150 mL).

The combined organic extracts were washed with brine, dried (Na₂SO₄) andthe solvent was removed under reduced pressure.

The residue was purified by flash chromatography over a column of silicausing CHCL₃-EtOH—NH₄OH (98.5:1.0:0.5) as the eluent to obtain 7d (0.503g): mp 138-145° C. dec; TLC, R_(f)0.29 (CHCl₃—MeOH—NH₄OH, 95:5:0.5).

EXAMPLE 4 Preparation of17-(Cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxy-5′-nitropyrido[2′,3′:6,7]morphinan(7e)

A stirred solution of naltrexone (4.26 g, 12.4 mmol),1-methyl-3,5-dinitropyridin-2-one (2.99 g; 15.0 mmol) in 2M methanolicammonia (200 mL) was heated under reflux at 70° C. for 24 h. Volatilematerials were removed under reduced pressure, the residue was dissolvedin minimum quantity of MeOH and slurried with silica gel. The driedslurry was applied to the top of a column of silica and eluted withCHCl₃ containing 0.1, 0.2, 0.3, 0.4 and 1.5% of MeOH. Fractionscontaining the product were pooled and the solvent was removed underreduced pressure to obtain 7e (3.01 g): mp, softens and foams at117-125° C., decomposes at 142-156° C.; TLC, R_(f)0.44(CHCl₃—MeOH—NH₄OH, 95:5:0.5).

EXAMPLE 5 Preparation of5′-Amino-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxypyrido[2′,3′:6,7]morphinan(7f)

The above nitropyridine (2.9 g, 6.6 mmol) was dissolved in warm EtOH(300 mL). To the solution was added, under an atmosphere of argon, 10%palladium on carbon (0.90 g) and the mixture was hydrogenated at 50 psiin a Paar shaker for 24 h. The mixture was filtered through a pad ofcelite under argon. The solvent was removed under reduced pressure toobtain 2.67 g of the amino compound 7f as a pure produce. Pm 202-204° C.dec; TLC, R_(f)0.34 (CHCl₃—MeOH, 9:1).

EXAMPLE 6 Preparation of5′-Amino-4′-cyano-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxythieno[2′,3′:7,6]morphinan(8a)

A stirred mixture of naltrexone (1.70 g; 5.0 mmol), malononitrile (0.33g; 5.0 mmol) and sulfur (0.16 g; 5.0 mmol) in EtOH (10 mL) was treateddropwise with morpholine (0.5 mL; 5.7 mmol) and stirred at roomtemperature for 24 h.

The mixture was concentrated under reduced pressure and the residue wastriturated with water. The water insoluble product was collected byfiltration, washed with water and dried. The crude product was purifiedby flash chromatography over a column of silica-using CHCl₃—MeOH (95:5)as the eluent to obtain 8a (0.56 g): mp 208-212° C. dec; TLC, R_(f)0.53(CHCl₃—MeOH, 9:1)

EXAMPLE 7 Preparation of5′-Amino-4′-carbomethoxy-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxythieno[2′,3′:7,6]morphinan(8b)

A stirred mixture of naltrexone (1.70 g; 5.0 mmol), methyl cyanoacetate(0.44 mL; 5.0 mmol) and sulfur (0.16 g; 5.0 mmol) in MeOH (10 mL) wastreated dropwise at room temperature with morpholine (0.5 mL; 5.7 mmol)and the mixture was then refluxed overnight. The mixture was allowed tocool to room temperature and the solid obtained was collected byfiltration. The crude product was purified by flash chromatography overa column of silica using CHCl₃—MeOH (98:2) as the eluent to obtain 8b(0.84 g): Mp 189-191° C. dec; TLC, R_(f) 0.51 (CHCl₃—MeOH, 9:1).

EXAMPLE 8 Preparation of5′-Amino-4′-carbethoxy-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxythieno[2′,3′:7,6]morphinan(8c)

A stirred mixture of naltrexone (1.70 g; 5.0 mmol), ethyl cyanoacetate(0.8 mL; 7.5 mmol) and sulfur (0.24 g; 7.5 mmol) in EtOH (10 mL) wastreated dropwise at room temperature with morpholine (0.87 mL; 10.0mmol) and the mixture was then refluxed overnight. The mixture wasallowed to cool to room temperature and poured over ice-water mixture(500 mL). The solid obtained was collected by filtration. The crudeproduct was purified by flash chromatography over a column of silicausing CHCl₃—MeOH (99:1) as the eluent to obtain Bc (1.1 g): mp 189-191°C. dec; TLC, R_(f)0.57 (CHCl₃—MeOH, 9:1)

EXAMPLE 9 Preparation of51-Amino-4′-benzyloxycarbonyl-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxythieno[2′,3′:7,6]morphinan(8d)

A stirred mixture of naltrexone (1.70 g; 5.0 mmol), benzyl cyanoacetate(1.31 g; 7.5 mmol) and sulfur (0.24 g; 7.5 mmol) in DMF (15 mL) wastreated dropwise at room temperature with morpholine (0.66 mL; 7.6 mmol)and the mixture was then heated under reflux at BOOC for 24 h. Thereaction mixture was allowed to cool to room temperature and poured overice-water mixture. The solid obtained was collected by filtration,washed with water and dried. The crude product was purified by flashchromatography over a column of silica using CHCl₃—MeOH (99:1) as theeluent to obtain 8d (1.16 g): mp 208-212° C. dec; TLC, R_(f) 0.69(CHCl₃—MeOH 9:1).

EXAMPLE 10 Preparation of5′-Amino-4′-aminocarbonyl-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxythieno[2′,3′:7,6]morphinan(8e)

A stirred mixture of naltrexone (1.7.0 g; 5.0 mmol), cyanoacetamide(0.63 g; 7.5 mmol) and sulfur (0.24 g; 7.5 mmol) in EtOH (20 mL) wastreated dropwise at room temperature with morpholine (0.66 mL; 7.6 mmol)and the mixture was then refluxed for 24 h. After allowing to cool toroom temperature, the reaction mixture was poured-over ice-watermixture. The solid obtained was collected by filtration, dissolved inCHCl₃ and washed with saturated aqueous NaHCO₃ followed by water. Theorganic layer was dried (Na₂SO₄), filtered, and the solvent was removedunder reduced pressure. The crude product was purified by flashchromatography over a column of silica using CHCl₃—MeOH (95:5) as theeluent to obtain 8e (0.82 g): *mp 250-264° C. dec; TLC, R_(f)0.39(CHCl₃—MeOH, 9:1).

EXAMPLE 11 Preparation of5′-Amino-4′-benzoyl-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5α-epoxythieno[2′,3′:7,6]morphinan(8f)

A stirred mixture of naltrexone (1.70 g; 5.0 mmol), benzoyl acetonitrile(0.725 g; 5.0 mmol) and sulfur (0.24 g; 7.5 mmol) in EtOH (12 mL) wastreated dropwise at room temperature with morpholine (0.66 mL; 7.6 mmol)and the mixture was then refluxed for 24 h. The reaction mixture wascooled and poured over ice-water mixture. The solid obtained wascollected by filtration, washed with water and dried. The crude productwas purified by flash chromatography over a column of silica usingCHCl₃—MeOH (99:1) as the eluent to obtain 8f (0.52 g): mp 190-194° C.dec; TLC, R_(f)0.61 (CHCl₃—MeOH, 9:1).

EXAMPLE 12

Biological Evaluations.

Radioligand Binding Assays. Mu binding sites were labeled using[³H]DAMGO (1-3 nM). Rat membranes were prepared each day using apartially-thawed frozen rat brain which was homogenized with a polytronin 10 mL/brain of ice cold 10 mM Tris-HCl, pH 7.0. Membranes were thencentrifuged twice at 30,000 g for 10 min and resuspended with ice-coldbuffer following each centrifugation. After the second centrifugation,the membranes were resuspended in 50 mM Tris-HCl₁, pH 7.4 (50 mL/brain)at 25° C. Incubations proceeded for 2 h at 25° C. in 50 mM Tris-HCl, pH7.4, along with a protease inhibitor cocktail (PIC). The nonspecificbinding was determined using 20 μM of levallorphan. Delta binding siteswere labeled using [³]DADLE (2 nM) and rat brain membranes. Ratmembranes were prepared each day using a partially thawed frozen ratbrain which was homogenized with a polytron in 10 mL/brain of ice cold10 mM Tris-HCl₁, pH 7.0. Membranes were then centrifuged twice at 30,000g for 10 min and resuspended with ice-cold buffer following eachcentrifugation. After the second centrifugation, the membranes wereresuspended in 50 mM Tris-HCl, pH 7.4 (50 mL/brain) at 25° C.Incubations proceeded for 2 h at 25° C. in 50 mM Tris-HCl pH 7.4,containing 100 mM choline chloride, 3 mM MnCl₂, and 100 nM DAMGO toblock binding to p sites, and PIC. Nonspecific binding was determinedusing 20 μM levallorphan. Kappa binding sites were labeled using[3H]U69,593 (2 nM). Guinea pig brain membranes were prepared each dayusing partially thawed guinea pig brain which was homogenized with apolytron in 10 mL/brain of ice cold 10 mM Tris-HCl, pH 7.0. Themembranes were then centrifuged twice at 30,000 g for 10 min andresuspended with ice-cold buffer following each centrifugation. Afterthe second centrifugation, the membranes were resuspended in 50 mMTris-HCl, pH 7.4 (75 mL/brain) at 25° C. Incubations proceeded for 2 hat 25° C. in 50 mM Tris-HCl, pH 7.4, containing 1 μg/mL of captopril andPIC. Nonspecific binding was determined using 1 μM U69,593. Each ³Hligand was displaced by 8-10 concentrations of test drug, two times.Compounds were prepared as 1 mM solution with 10 mM Tris buffer (pH 7.4)containing 10% DMSO before drug dilution. All drug dilutions were doneat 10 mM Tris-HCl, pH 7.4, containing 1 mg/mL bovine serum albumin. Allwashes were done with ice-cold 10 mM Tris-HCl, pH 7.4. The IC₅₀ andslope factor (N) were obtained by using the program MLAB-PC (CivilizedSoftware, Bethesda, Md.). Ki values were calculated according to theequation Ki=IC₅₀/(1+[L]/Kd).

Bioassays in GPI and MVD smooth muscle preparations.Electrically-induced smooth muscle contractions of mouse vas deferensand strips of guinea pig ileum longitudinal muscle myenteric plexus wereused. Tissues came from maile-ICR mice weighing 25-40 g and male Hartleyguinea pigs weighing 250-500 g. The tissues were tied to gold chain withsuture silk, suspended in 20 mL baths containing 37° C. oxygenated (95%O₂, 5% CO₂) Krebs bicarbonate solution (magnesium free for the MVD), andallowed to equilibrate for 15 min. The tissues were then stretched tooptimal length previously determined to be 1 g tension (0.5 g for MVD)and allowed to equilibrate for 15 min. The tissues were stimulatedtransmurally between platinum wire electrodes at 0.1 Hz, 0.4 ms pulses(2-ms pulses for MVD), and supramaximal voltage. An initialdose-response curve of DPDPE or PL-017 was constructed at the start ofeach assay to establish tissue effects, allowing each tissue to be usedas its own control.

Tissues not producing typical results were not used. Experimentalcompounds were added to the baths in 14-60 μL volumes. Succeeding dosesof argonist were added cumulatively to the bath at 3 minute intervals toproduce a concentration-response curve. The tissues were then washedextensively with fresh buffer until the original contraction height wasre-established. Agonist effects of the compounds at 1 μM were measuredas percent inhibition of contraction height 10 min after addition to thebath. Antagonist effects to DPDPE and PL-017 were assayed afterincubation of the tissues with 1 μM concentration of the compound in thebath for 30 minutes. The tissues were then washed with fresh buffer for30 min, and the agonist dose-response curve was repeated. Rightwardshifts in the dose-response curves were calculated by dividing theantagonized dose-response curve IC₅₀ value by the unantagoniced IC₅₀value. IC₅₀ values represent the mean of two to four tissues. IC₅₀estimates and their associated standard errors were determined by usinga computerized nonlinear least-squares method.

The following biological results discussed below were obtained.

The δ, μ and κ opioid receptor binding profile of the pyridomorphinansis given in Table 1, and that of thienomorphinans is given in Table 2.The opioid antagonist and agonist potencies of the target compounds inthe MVD and GPI smooth muscle preparations are listed in Table 3. All ofthe 5′-substituted pyridomorphinans bind with high affinities (Ki<10 nM)at the δ receptor. Although the substituted compounds show slightreduction in binding potencies relative to the parent compound 7a, theyretain the δ selective binding profile of the parent compound. The μ/δand κ/δ selectivity ratios are differentially affected by differentsubstituents. The bromine at the 5′-position (7b) increases δselectivity by decreasing relative binding potencies at both μ and κsites. The ester compound 7d on the other hand has increased μ/δselectivity ratio but lower κ/δ selectivity ratio than the parentcompound. The bromo compound, besides being the most potent and δselective in binding assays, is also the most potent δ antagonist in theMVD with a Ke of (3.1 nM).

All of the thienomorphinans bind with high affinity to the δ receptor(Ki<14 nM). Most of the compounds also bind to the μ and particularlythe κ site with high affinity thus leading to generally low bindingselectivity ratios. The substituents at the 4′-position (equivalent tothe indolic nitrogen position of NTI and BNTI) are tolerated at the δreceptor site equally well despite the differences in the steric bulk ofthe substituents. Interestingly, compound 8d carrying the bulky benzylester substituent shows marginally improved μ/δ and κ/δ selectivityratios due to decreased binding affinity at the μ and κ receptors. Thiscompound also displays the highest δ antagonist activity in the MVD witha Ke of 5.0 nM and weak agonist activity in the GPI with 40% inhibitionat 1 μM concentration. These results indicate that the introduction ofsubstituents on these functionalized frameworks increases binding andantagonist potency at the δ receptor and/or decreases binding andactivity at the μ and κ receptors. TABLE 1 Opioid Receptor BindingAffinities of Pyridomorphinans in Rat or Guinea Pig Brain Membranes

Selectivity Ki (nm) ± SEM Ratio compd. R δ^(a) μ^(b) κ₁ ^(c) μ/δ κ₁δ7a^(d) H 0.78 ± 1.5 ± 0.09 8.8 ± 0.69 1.9 11 0.06 7b Br 1.2 ± 0.13 15.5± 1.0 55.7 ± 7.0 13 46 7c CN 4.5 ± 0.28 16.0 ± 1.8 33.9 ± 2.0 3.6 7.5 7dCO₂C₂H₅ 4.2 ± 0.27 37.0 ± 3.4 9.6 ± 0.93 8.8 2.3 7e NO₂ 5.5 ± 0.67 17.5± 2.0 92.0 ± 12.8 3.2 17 7f NH₂ 8.0 ± 0.3 12.8 ± 0.93 12.0 ± 1.2 1.6 1.5^(a)Displacement of [³H] DADLE (1.3-2.0 nM) in rat brain membranes using100 nM DAMGO to block binding to μ-sites.^(b)Displacement of [³H] DAMGO (1.4-2.0 nM) in rat brain membranes.^(c)Displacement of [³H] U69,593(1.2-2.2 nm) in guinea pig brainmembranes.^(d)Data taken from Ananthan, S., et al., Synthesis, Opioid ReceptorBinding, and Biological Activities of Naltrexone-Derived Pyrido- andPyrimidomorphinans, J. Med. Chem. 1999, 42, in press.

TABLE 2 Opioid Receptor Binding Affinities of Thienomorphinans in Rat orGuinea Pig Brain Membranes

Selectivity Ki (nm) ± SEM Ratio compd. R δ^(a) μ^(b) κ₁ ^(c) μ/δ κ₁δ 8aCN 2.6 ± 0.11 5.5 ± 0.2 1.5 ± 0.12 2.1 0.6 8b CO₂CH₃ 6.6 ± 0.3 29.0 ±4.0 8.7 ± 0.34 4.4 1.3 8c CO₂C₂H₅ 5.0 ± 0.2 20.0 ± 1.0 9.0 ± 0.81 4.01.8 8d CO₂CH₂C₆H₅ 7.0 ± 0.3 61.0 ± 3.0 48.0 ± 3.0 8.7 6.9 8e CONH₂ 3.7 ±0.2 21.0 ± 1.3 2.0 ± 0.2 5.7 0.5 8f COC₆H₅ 14.0 ± 0.7 50.0 ± 3.0 14.0 ±0.7 3.6 1.0^(a)Displacement of [³H] DADLE (1.3-2.0 nM) in rat brain membranes using100 nM DAMGO to block binding to μ-sites.^(b)Displacement of [³H] DAMGO (1.4-2.0 nM) in rat brain membranes.^(c)Displacement of [³H] U69,593 (1.2-2.2 nm) in guinea pig brainmembranes.

TABLE 3 Opioid Antagonist and Agonist Potencies of Pyrido- andThienomorphinans in the MVD and GPI Preparations agonist activity MVDGPI antagonist activity IC₅₀ (nM) IC₅₀ (nM) DPDPE (δ)^(a) MVD PL017(μ)^(b) GPI K_(e) selectivity or % max or % max No IC₅₀ ratio K_(e)nM^(c) IC₅₀ ratio K_(e) nM^(c) ratio μδ resp^(d) resp^(d) 7a^(e) 27.9 ±1.2 37 7.08 ± 3.44 164 4.4 0% 0% 7b  325 ± 127 3.1 43.9 ± 25.6 23 14 0%0% 7c 23.6 ± 2.2 44 2.2 ± 1.1 f — 0% 0% 7d 50.1 ± 4.9 20 14.5 ± 5.2  743.7 0% 0% 7e 20.7 ± 4.2 51  4.7 ± 0.59 271 5.3 14%  0% 7f 43.3 ± 9.0 2623.4 ± 4.8  49 1.9 6% 0% 8a 109.6 ± 12.1 9.6 160.3 ± 41.6  8.7 0.9 0% 0%8b  53.5 ± 10.1 21 39.1 ± 11.6 35 1.7 0% 0% 8c 19.8 ± 6.6 68 46.0 ± 21.926 0.4 11%  0% 8d 289 ± 13 5.0 g — — 11%  40%  8e 118.6 ± 38.4 10 47.8 +10.7 24 2.4 5% 4% 8f 24.4 ± 4.0 46 21.6 ± 7.7  62 1.3 15%  25% ^(a)DPDPE as the agonist.^(b)PL-017 as the agonist.^(c)K_(C) (nM) = [antagonist]/(IC₅₀ ratio-1), where the IC₅₀ ratio isthe IC₅₀ of the agonist in the presence of antagonist divided by thecontrol IC₅₀ in the same preparation (n = 3).^(d)Agonist activity, percentage inhibition of contraction at 1 μM.^(e)Data for 7a included for comparison. Data taken from Ananthan etal., supra.f The agonist effects precluded the determination of antagonist effects.g IC₅₀ ratio was not statistically different from 1.

The pharmaceutically acceptable effective dosage of the active compoundof the present invention to be administered is dependent on the speciesof the warm-blooded animal (mammal), the body weight, age and individualcondition, and on the form of administration.

The pharmaceutical composition may be oral, parenteral, suppository orother form which delivers the compounds used in the present inventioninto the bloodstream of a mammal to be treated.

The compounds of the present invention can be administered by anyconventional means available for use in conjunction withpharmaceuticals, either as individual therapeutic agents or in acombination of therapeutic agents. They can be administered alone, butgenerally administered with a pharmaceutical carrier selected on thebasis of the chosen route of administration and standard pharmaceuticalpractice.

The dosage administered will, of course, vary depending upon knownfactors, such as the pharmacodynamic characteristics of the particularagent and its mode and route of administration; the age, health andweight of the recipient; the nature and extent of the symptoms, the kindof concurrent treatment; the frequency of treatment; and the effectdesired. A daily dosage of active ingredient can be expected to be about0.001 to 1000 milligram (mg) per kilogram (kg) of body weight, with thepreferred dose being 0.1 to about 30 mg/kg.

Dosage forms (compositions suitable for administration) typicallycontain from about 1 mg to about 100 mg of active ingredient per unit.In these pharmaceutical compositions, the active ingredient willordinarily be present in an amount of about 0.5-95% by weight based onthe total weight of the composition.

The active ingredient can be administered orally in solid dosage forms,such as capsules, tablets, and powders, or in liquid dosage forms, suchas elixirs, syrups, and suspensions. It can also be administeredparenterally, in sterile liquid dosage forms. The active ingredient canalso be administered intranasally (nose drops) or by inhalation.

Other dosage forms are potentially possible such as administrationtransdermally, via a patch mechanism or ointment.

Gelatin capsules contain the active ingredient and powdered carriers,such as lactose, starch, cellulose derivatives, magnesium stearate,stearic acid, and the like.

Similar diluents can be used to make compressed tablets. Both tabletsand capsules can be manufactured as sustained release products toprovide for continuous release of medication over a period of hours.Compressed tablets can be sugar-coated or film-coated to mask anyunpleasant taste and protect the tablet from the atmosphere, or entericcoated for selective disintegration in the gastrointestinal tract.

Liquid dosage forms for oral administration can contain coloring andflavoring to increase patient acceptance.

In general, water, a suitable oil, saline, aqueous dextrose (glucose),and related sugar solutions and glycols such as propylene glycol orpolyethylene glycols are suitable carriers for parenteral solutions.Solutions for parenteral administration preferably contain awater-soluble salt of the active ingredient, suitable stabilizingagents, and, if necessary, buffer substances. Antioxidizing agents suchas sodium bisulfite, sodium sulfite, or ascorbic acid, either alone orcombined, are suitable stabilizing agents. Also used are citric acid andits salts and sodium EDTA. In addition, parenteral solutions can containpreservatives, such as benzalkonium chloride, methyl- or propylparaben,and chlorobutanol.

Suitable pharmaceutical carriers are described in Remington'sPharmaceutical Sciences, Mack Publishing Company, a standard referencetext in this field.

Useful pharmaceutical dosage forms for administration of the compoundsaccording to the present invention can be illustrated as follows:

Capsules

A large number of unit capsules are prepared by filling standardtwo-piece hard gelatin capsules each with 100 mg of powdered activeingredient, 150 mg of lactose, 50 mg of cellulose, and 6 mg of magnesiumstearate.

Soft Gelatin Capsules

A mixture of active ingredient in a digestible oil such as soybean oil,cottonseed oil or olive oil is prepared and injected by means of apositive displacement pump into gelatin to form soft gelatin capsulescontaining 100 mg of the active ingredient. The capsules are washed anddried.

Tablets

A large number of tablets are prepared by conventional procedures sothat the dosage unit was 100 mg of active ingredient, 0.2 mg ofcolloidal silicon dioxide, 5 mg of magnesium stearate, 275 mg ofmicrocrystalline cellulese, 11 mg of starch, and 98.8 mg of lactose.Appropriate coatings may be applied to increase palatability or delayabsorption.

Various modifications of the invention in addition to those shown anddescribed-herein will be apparent to those skilled in the art from theforegoing description. Such modifications are also intended to fallwithin the scope of the appended claims.

The foregoing disclosure includes all the information deemed essentialto enable those skilled in the art to practice the claimed invention.Because the cited applications may provide further useful information,these cited materials are hereby incorporated by reference in theirentirety.

The foregoing description of the invention illustrates and describes thepresent invention. Additionally, the disclosure shows and describes onlythe preferred embodiments of the invention but, as mentioned above, itis to be understood that the invention is capable of use in variousother combinations, modifications, and environments and is capable ofchanges or modifications within the scope of the inventive concept asexpressed herein, commensurate with the above teachings and/or the skillor knowledge of the relevant art. The embodiments described hereinaboveare further intended to explain best modes known of practicing theinvention and to enable others skilled in the art to utilize theinvention in such, or other, embodiments and with the variousmodifications required by the particular applications or uses of theinvention. Accordingly, the description is not intended to limit theinvention to the form disclosed herein. Also, it is intended that theappended claims be construed to include alternative embodiments.

1. A method for treating a patient suffering from pain which comprisesadministering to the patient a pain treating effective amount of atleast one compound represented by the formulae I and II

wherein each of Y, X and R individually is selected from the groupconsisting of hydrogen, hydroxyl, halo, CF₃, NO₂, CN, NH₂, COR¹ andCO₂R² wherein R¹ is selected from the group consisting of alkyl, aryl,alkaryl, and NH₂, and R² is selected from the group consisting of alkyl,aryl, and aralkyl, and provided that at least one of Y, X and R informula I is other than hydrogen; or pharmaceutically acceptable saltthereof.
 2. The method of claim 1 wherein the compound is represented byformula I wherein X is H, Y is H and R is Br.
 3. The method of claim 1wherein the compound is represented by formula I wherein X is H, Y is Hand R is CN.
 4. The method of claim 1 wherein the compound isrepresented by formula I wherein X is H, Y is H and R is CO₂R².
 5. Themethod of claim 1 wherein the compound is represented by formula Iwherein X is H, Y is H and R is NO₂.
 6. The method of claim 1 whereinthe compound is represented by formula I wherein X is H, Y is H and R isNH₂.
 7. The method of claim 1 wherein the compound is represented byformula II wherein X is NH₂, and R is H.
 8. The method of claim 1wherein the compound is represented by formula II wherein X is NH₂, andR is CN.
 9. The method of claim 1 wherein the compound is represented byformula II wherein X is NH₂, and R is CO₂R².
 10. The method of claim 1wherein the compound is represented by formula II wherein X is NH₂, andR is H by formula II wherein X is NH₂, and R is CONH₂.
 11. A method fortreating a patient in need of an immunomodulatory agent which comprisesadministering to the patient an immunomodulatory effective amount of atleast one compound represented by the formulae I and II

wherein each of Y, X and R individually is selected from the groupconsisting of hydrogen, hydroxyl, halo, CF₃, NO₂, CN, NH₂, COR¹ andCO₂R² wherein R¹ is selected from the group consisting of alkyl, aryl,alkaryl, and NH₂, and R² is selected from the group consisting of alkyl,aryl, and aralkyl, and provided that at least one of Y, X and R informula I is other than hydrogen; or pharmaceutically acceptable saltthereof.
 12. A method for treating a patient suffering from drug abusewhich comprises administering to the patient an effective amount fortreating drug abuse of at least one compound represented by the formulaeI and II

wherein each of Y, X and R individually is selected from the groupconsisting of hydrogen, hydroxyl, halo, CF₃, NO₂, CN, NH₂, COR¹ andCO₂R² wherein R¹ is selected from the group consisting of alkyl, aryl,alkaryl, and NH₂, and R² is selected from the group consisting of alkyl,aryl, and aralkyl, and provided that at least one of Y, X and R informula I is other than hydrogen; or pharmaceutically acceptable saltthereof.
 13. The method of claim 12 in which the drug abuse comprisescocaine or methamphetamine abuse.
 14. A method for treating a patientsuffering from dependence on or tolerance to a μ agent which compriseadministering to the patient at least one the compound represented bythe formulae I and II

wherein each of Y, X and R individually is selected from the groupconsisting of hydrogen, hydroxyl, halo, CF₃, NO₂, CN, NH₂, COR¹ andCO₂R² wherein R¹ is selected from the group consisting of alkyl, aryl,alkaryl, and NH₂, and R² is selected from the group consisting of alkyl,aryl, and aralkyl, and provided that at least one of Y, X and R informula I is other than hydrogen; or pharmaceutically acceptable saltthereof; in an amount effective to modulate the tolerance to ordependence on μ agonists.